Supplementary header for multifabric and high port count switch support in a fibre channel network

Accordingly, there is disclosed herein an augmented Fibre Channel (FC) frame format which may provide support for multiple fabric FC networks, and may improve the performance of modularly-constructed switches. In one embodiment, the augmented FC frame format is modulated on a carrier signal and the frame includes: a start-of-frame field; a supplementary header field that follows the start-of-frame field; a frame header field that follows the supplementary header field; a cyclic redundancy code (CRC) checksum field; and an end-of-frame field that follows the CRC checksum field. The supplementary header field may include a destination tag that identifies a target fabric to which the frame is directed. Alternatively, or in addition, the supplementary header field may include an egress port identifier that identifies a switch port through which the frame is to exit a switch. The supplementary header may also include flags to request special handling by the receiver.